OP SOUTHERN INDIA. 115 



Ba. Psammotella, Blainv.^ 1824. This includes a few yellowish or purplish 

 coloured species with a thin epidermis ; posteriorly slightly rostrated and rounded ; 

 the fulcrum is very strong, and the margin in front of the hinge somewhat 

 thickened, as if indicating a lateral tooth. The type of the sub-genus is Hiatula 

 (SoletelUna) suh-radiata^ Desh. 



35. Psammotcea, Lamck., 1818, (Capsella, Desh.; see Eeeve in Conch. 

 Icon. x). Shell transversally elongated, thin, beaks slightly prominent, the posterior 

 side indistinctly ridged, scarcely less high than the anterior, sub-equilateral, 

 coYcred with an olivaceous epidermis ; hinge with one tooth in the left and two 

 in right valve, all three short, blunt, and grooved ; pallial sinus deep. This includes 

 a number of eastern shells, in which the epidermis is strongly developed and 

 the shelly part thin ; they appear partially to live in brackish water ; Fsammotcea 

 Layardiy Desh., may be considered as the type. 



4. Sanguinolaria, Lam., 1799. Shell largely oblong, thin, posteriorly 

 considerably attenuated and sub-angular; hinge with two approximate, partially 

 bifid teeth in each valve; pallial sinus very wide, somewhat irregular. Eeeve 

 describes five species, most of which are rose coloured. S. sangumolenta, 

 Gmelin, is the type of the genus ; the shells are distinguished by their largely 

 oval and compressed form and their thin structure. 



,5. Blizia, Gray, 1852. Shell compressed, thin, like Sanguinolaria, but sub^ 

 orbicular in shape, and not ridged posteriorly ; the anterior side much shorter ; hino'e 

 wdth three teeth in the left and two in the right valve ; in the former the central 

 indistinctly bifid, and the posterior are in both almost horizontally prolongated. 

 Reeve describes two species as SoletelUna ( = Siatula), the well known JE, orhu 

 culata from Sumatra, and another, JE. reversa, from Malacca; the latter seems 

 hardly to differ from the former. 



b. Sub-family— TMLLININJ^, 



In this sub-family are included the species which are by older conchologists 

 usually called Tellina. The animals of these species have, as a rule, very lono^, 

 thin siphons with entire orifices, and the two plumes composing the gills anteriorly 

 grown together in one plane, but posteriorly more or less free, palpi very 

 large ; the shells are peculiarly attenuated and compressed posteriorly ; the surface 

 is very regularly concentrically striated, and in the larger number of them the 

 hinge is furnished with lateral teeth ; those of the left valve are, however, generally 

 smaller or even obsolete ; the posterior gape is always distinct, though narrow, 

 but the anterior is only occasionally traceable ; the ligament is strong, the fulcra 

 not very prominent, the pallial sinus usually very large. Their geographical 

 distribution is world-wide, and the first species occur in the Jurassic period; 

 they are, as a rule, true marine shells. 



6. Macoma, Leach, 1819. Shell slightly inflated, or compressed, cardinal 

 teeth small, sometimes nearly obsolete, the laterals are, as a rule, not developed 

 at all, occasionally there is a thickening of the margins observablco The sheik 



